Semiconductor wafer holder and electroplating system for plating a semiconductor wafer

ABSTRACT

A semiconductor wafer holder includes first and second holding members between which a semiconductor wafer is held. The second holding member includes a second conductive element placed in contact with a first conductive element of the first holding member and the semiconductor wafer. A ring clamp is used to press the second holding member against the first holding member for holding of the semiconductor wafer.

This is a divisional application of Ser. No. 09/990,387, filed Nov. 23,2001, now U.S. Pat. No. 7,022,211 which is a continuation application ofSer. No. 09/463,698, filed Jan. 31, 2000, now abandoned, which is a 371of PCT/JP99/02576, filed May 18, 1999.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a semiconductor wafer holder and anelectroplating system for plating a semiconductor wafer. Thesemiconductor wafer holder is designed to hold a semiconductor waferduring electrolytic plating.

2. Description of Related Art

A conventional semiconductor wafer holder holds a semiconductor wafer sothat a conductive pin is placed in contact with a conductive layer ofthe semiconductor wafer during electrolytic plating. The wafer holdertogether with the semiconductor wafer is immersed in an electrolyte bathwithin which an electrolytic solution is contained. Electrical currentis supplied to the semiconductor wafer through the electrolytic solutionand the conductive pin for electrolytic plating of the semiconductorwafer.

With such an arrangement, however, it is not easy to mount thesemiconductor wafer to the holder. Also, the conductive pin can not bereliably contacted with the conductive layer of the semiconductor wafer.

In view of the foregoing, it is a first object of the present inventionto provide a semiconductor wafer holder which enables ready mounting ofa semiconductor wafer and reliable application of electrical current toa conductive layer of the semiconductor wafer.

The prior art semiconductor wafer holder includes a packing for sealingof the conductive pin. The packing extends between the semiconductorwafer and a holding element by which the semiconductor wafer is held. Aplurality of bolts are tightened to clamp the packing, whereby uniformpressure is exerted on the packing to seal the conductive pin.

Such an approach is, however, cumbersome. It is also difficult to applyuniform torque to each bolt. Uneven application of torque may cause theelectrolytic solution to reach the conductive pin.

In view of the foregoing, it is a second object of the present inventionto provide a semiconductor wafer holder which facilitates clamping of apacking and enables uniform application of a clamping force to theperimeter edge of the packing.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda semiconductor wafer holder comprising a first holding member, and asecond holding member with a packing adapted to cooperate with the firstholding member to sandwich a semiconductor wafer. The semiconductorwafer is exposed through inside of the packing.

The first holding member includes a first conductive element adapted forelectrical connection with an external electrode.

The second holding member includes a second conductive element adaptedfor contact with the first conductive element of the first holdingmember and a conductive layer of the semiconductor wafer and sealed bythe packing.

In the first aspect of the invention, it is preferable that the packinghas an annular shape, and the first conductive element is arrangedadjacent to the outer periphery of the semiconductor wafer held betweenthe first and second holding members.

It is also preferable that the packing has an inverted U-shaped section,with opposite end projections placed in contact with the first holdingmember and the semiconductor wafer, respectively, and the packingincludes a hole defined between the end projections, the secondconductive element being received in the hole.

The second conductive element preferably has an inverted U-shapedsection, with two end projections configured to bridge between the firstconductive element and the conductive layer of the semiconductor wafer.A resilient member is preferably used to mount the second conductiveelement within the hole.

In another embodiment, a semiconductor wafer holder comprises a firstholding member including a first conductive element, and a secondholding member including a second conductive element, wherein the firstholding member and the second holding member are operatively associatedwith each other so as to releasably hold a semiconductor wafertherebetween, and the first conductive element and the second conductiveelement are maintained out of contact with a plating liquid, and whereinthe second conductive element of the second holding member is held incontact with the first conductive element of the first holding memberand the semiconductor wafer when the semiconductor wafer is sandwichedbetween the first holding member and the second holding member.

According to a second aspect of the present invention, there is provideda semiconductor wafer holder comprising a plate-like first holdingmember, an annular second holding member with a packing mounted thereon,a ring clamp operable to press the second holding member against thefirst holding member so as to hold a semiconductor wafer therebetween,and a conductive member placed in contact with the conductive layer ofthe semiconductor wafer and sealed by the packing.

In another embodiment, a semiconductor wafer holder comprises a firstholding member in the form of a plate, an annular second holding memberincluding a packing mounted thereon, and a ring clamp operable to pressthe second holding member against the first holding member so as to holda semiconductor wafer therebetween.

The first holding member includes a first conductive element arrangedadjacent to the outer periphery of the semiconductor wafer held betweenthe first and second holding member.

Also, the packing of the second holding member includes a secondconductive element placed in contact with the first conductive elementand the conductive layer of the semiconductor wafer held between thefirst and second holding members and sealed by the packing.

It is preferable that the ring clamp includes a plurality of protrusionsformed on its outer periphery and arranged at given intervals, and thefirst holding member includes a plurality of pawls of an invertedL-shape. The plurality of protrusions are slid below the plurality ofpawls to thereby clamp the first and second holding members togetherwhen the ring clamp is rotated by a given angle.

It is also preferable that the first holding member and the secondholding member are connected by and pivoted about a hinge mechanism.

It is further preferable that the second holding member and the ringclamp are connected by a ring retainer and capable of rotation on thesecond holding member by a given angle.

In another embodiment, a semiconductor wafer holder comprises a firstholding member, a second holding member and a clamping ring movablebetween a clamp position and an open position and including a lockingmember.

The first and second holding members are cooperative to releasably holda semiconductor wafer therebetween.

One of the first and second holding members includes a lockable portionto be releasably engaged with the locking member.

The locking member is engaged with the lockable portion so as to lockthe first and second holding members together when the clamping ring isheld in the clamp position.

Also, the first holding member and the second holding member areunlocked when the clamping ring is held in the open position, wherebythe semiconductor wafer can be loaded between and unloaded from thefirst and second holding members.

According to a third aspect of the present invention, there is providedan electroplating system for plating a semiconductor wafer comprising asemiconductor wafer holder as set forth in any one of the foregoingembodiments.

In the third aspect of the invention, an electroplating system forplating a semiconductor wafer, comprises a loading/unloading station fortransferring the semiconductor wafer from a wafer cassette to asemiconductor wafer holder and vice versa, and

a plating bath station including a plating bath within which a platingliquid is contained, the semiconductor wafer holder with thesemiconductor wafer mounted therein being immersed in the plating liquidwhereby the semiconductor wafer is plated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the outer appearance of asemiconductor wafer holder according to one embodiment of the presentinvention;

FIG. 2 is a sectional view illustrating the positional relationshipbetween a first conductive element and a packing when a second holdingmember is placed on a first holding member of the semiconductor waferholder shown in FIG. 1;

FIG. 3A is a front view of the semiconductor wafer holder;

FIG. 3B is a side view of the semiconductor wafer holder;

FIG. 4 is a schematic view of an electroplating system according toanother embodiment of the present invention;

FIG. 5 is a sectional view of another embodiment of the semiconductorwafer holder, illustrating the positional relationship between a firstconductive element and a packing when a second holding member is placedon a first holding member of the semiconductor wafer holder;

FIG. 6 is a sectional view of one form of a hinge mechanism;

FIG. 7A is a perspective view showing the outer appearance of asemiconductor wafer holder according to another embodiment of thepresent invention, with a first holding member in its open position;

FIG. 7B is an enlarged view of a portion B encircled in FIG. 7A;

FIG. 8 is a perspective view showing the outer appearance of thesemiconductor wafer holder shown in FIG. 7A, with the first holdingmember in its closed position;

FIG. 9 is a sectional view taken along the line C-C of FIG. 8;

FIG. 10 is a sectional view showing the positional relationship betweenthe first conductive element and a semiconductor wafer during clamping;

FIG. 11 is a sectional view showing the positional relationship betweena conductive member and a semiconductor wafer during clamping;

FIG. 12 is a side view of an electroplating system for plating asemiconductor wafer, made according to a different embodiment of thepresent invention;

FIG. 13 is a plan view of the electroplating system;

FIG. 14A is a sectional view of one form of a holder clamp; and

FIG. 14B is a sectional view of one form of a semiconductor waferholder.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described with reference to thedrawings. FIGS. 1, 2, 3A and 3B show a semiconductor wafer holderaccording to one embodiment of the present invention. FIGS. 7A, 7B, 8, 9and 10 show another embodiment of the semiconductor wafer holderaccording to the present invention.

FIG. 1 is a perspective view showing the outer appearance of asemiconductor wafer holder according to one embodiment of the presentinvention. As shown, a holder 10 includes a first, plate-like holdingmember 11 made of an electrically insulative material (such as syntheticresin), and a second, plate-like holding member 12 made of anelectrically insulative material (such as synthetic resin) and providedwith an annular seal or packing 13. The second holding member 12 isconnected to the first holding member 11 by means of a hinge mechanism14. A handle 15 is formed at one end of the first holding member 11remote from the hinge mechanism 14.

A recess is formed in the upper surface of the first holding member 11to receive a semiconductor wafer 16. The recess is substantiallyidentical in shape to the semiconductor wafer 16. A plurality of firstconductive elements 17 (four conductive elements are shown) are arrangedin the outer periphery of the recess in a circumferentially equallyspaced relationship. The top surface of each of the first conductiveelements 17 is substantially coincident with the top surface of thefirst holding member 11. The second holding member 12 has a centralopening 12 a which has an inner diameter slightly smaller than thediameter of the semiconductor wafer 16. An annular packing 13 is placedon the second holding member 12 and secured to the perimeter edge of theopening 12 a.

The packing 13 has an inverted U-shaped section, with opposite endprojections 13 a, 13 b. The packing 13 has a width so that the endprojections 13 a, 13 b are contacted with the upper surface of the firstholding member 11 and the surface of the semiconductor wafer 16,respectively. The end of the packing 13 projects from the upper surfaceof the second holding member 12 by a predetermined distance. A pluralityof holes 13 c (four are shown) are formed in the packing 13 to receive aplurality of corresponding second conductive elements 18 which willlater be described. The holes 13 c are arranged between the endprojections 13 a, 13 b and spaced at given intervals.

With this arrangement, the second holding member 12 is placed on thefirst holding member 11 through the hinge mechanism 14 after thesemiconductor wafer 16 is inserted within the recess of the firstholding member 11. At this time, the end projections 13 a, 13 b of thepacking 13 are brought into contact with the upper surface of the firstholding member 11 and the surface of the semiconductor wafer 16,respectively. The first holding member 11 cooperates with the packing 13to sandwich the perimeter edge of the semiconductor wafer 16. Thesurface of the semiconductor wafer 16 is exposed through the opening 12a of the second holding member 12.

FIG. 2 illustrates the positional relationship between the firstconductive elements 17 and the packing 13 when the second holding member13 is placed on the first holding member 11. As shown, the endprojections 13 a, 13 b of the packing 12 are placed in contact with theupper surface of the first holding member 11 and the upper surface ofthe semiconductor wafer 16, respectively. The second conductive elements18 have a cylindrical configuration. A slot 18 a is formed in one end ofeach of the second conductive elements 18 to provide two end projections18 b, 18 c. The second conductive element 18 thus has an invertedU-shaped section. The second conductive element 18 is attached to thesecond holding member 12 by a spring 19 so that the end projections 18b, 18 c are in contact with a conductive layer on the top of thesemiconductor wafer 16 and the upper surface of the first conductiveelement 17, respectively. A conductive member 20 extends through thefirst holding member 11. The first conductive element 17 is connectedthrough the conductive member 20 to an external electrode (not shown).

FIGS. 3A and 3B show the state in which the second holding member 12 isplaced on the first holding member 11. FIGS. 3A and 3B are front andside views of the wafer holder 10. As shown, one end of the firstholding member 11, which includes the handle 15, and one end of thesecond holding member 12 remote from the hinge mechanism 14 are securedby a clamp 21. By this arrangement, the semiconductor wafer 16 is heldbetween the first holding member 11 and the packing 13, and theconductive member 20 is reliably electrically connected to theconductive layer of the semiconductor wafer 16 through the firstconductive elements 17 and the second conductive elements 18. Asmentioned earlier, the conductive layer of the semiconductor wafer 16 isconnected to the external electrode.

FIG. 4 is a schematic view of an electroplating system with thesemiconductor wafer holder 10. In this figure, 30 denotes a plating bathwithin which an anode 31 and the semiconductor wafer holder 10 areplaced. A pump 35 is used to send an electrolytic solution to theplating bath 30 through a filter 32. Part of the electrolytic solutionwhich overflows from the plating bath 30 is returned to the pump forcirculation through the system. A direct current source 34 has apositive terminal connected to the anode and a negative terminalconnected to an external electrode 33. The semiconductor wafer is platedupon supply of direct current from the direct current source 34.

As mentioned earlier, the wafer holder includes two separate conductors(the first and second conductive elements 17, 18) mounted to the firstand second holding members 11, 12, respectively. The semiconductor wafer16 is conveniently contained in the recess of the first holding member11, and the conductive member 20 extends through the first holdingmember 11. The second conductive elements 18 as a conductive pin aremounted to the other, second holding member 12. This arrangementfacilitates mounting of the semiconductor wafer 16. The secondconductive elements 18 have an inverted U-shaped section and are mountedto the second holding member 12 by means of the spring 19. The two endprojections of each of the second conductive elements 18 are in contactwith the first conductive elements 17 and the conductive layer of thesemiconductor wafer 16, respectively. This arrangement enables reliablesupply of current to the conductive layer if, for example, the top ofthe semiconductor wafer 16 is not coincident with the top of the firstconductive element 17 as shown in FIG. 5.

FIG. 6 shows one form of the hinge mechanism 14. The hinge mechanism 14includes a hinge body 14 a secured to the first holding member 11 and ahinge pin 14 b secured to the second holding member 12 for engagementwith the hinge body 14 a.

Illustratively, the springs 19 are used to mount the second conductiveelements 18 to the second holding member. However, any other resilientmaterials may, alternatively, be employed.

FIGS. 7A, 7B and 8 are perspective views showing the outer appearance ofa semiconductor wafer holder according to the present invention. Asshown, a wafer holder 110 includes a plate-like first holding member111, a second holding member 112 to which an annular seal or packing 113is mounted, and a ring clamp 114.

The first holding member 111 is made of an electrically insulativematerial (such as synthetic resin). The first holding member 111 is inthe form of a rectangular plate and has a central recess within which asemiconductor wafer 116 is placed. A plurality of first conductiveelements 117 (eight conductive elements are shown) are located adjacentto the perimeter edge of the central recess and arranged in acircumferentially equally spaced relationship. The tops of the firstconductive elements 117 are substantially coincident with that of thefirst holding member 111. A plurality of pawls 120 (eight are shown) arearranged outside of the first conductive elements 117 and spaced atequal intervals. The pawls 120 have an inverted L-shape.

The second holding member 112 is made of an electrically insulativematerial (such as synthetic resin). As shown, the second holding member112 includes a ring 112 a and a straight arm 112 b integrally formedwith the ring 112 a. The packing 113 has an inverted U-shape and is madeof an electrically insulative material such as rubber and other elasticmaterials. As shown, the packing 113 is attached to one side of the ring112 a of the second holding member 112. A plurality of holes 113 a(eight holes are shown) are formed, at equal intervals, in the packing113 and located between its opposite end projections. Inserted withinthe holes 113 a are a plurality of second conductive elements 118 whichwill later be described (see FIG. 7B).

A plurality of protrusions 114 b (eight protrusions are shown) extendfrom the outer periphery of the ring clamp 114 and are arranged at givenintervals. A plurality of guide slots 114 a (four slots are shown) areformed in the upper side of the ring clamp 114 and arranged at givenintervals. A plurality of ring retainers 119 are formed on the topsurface of the ring 112 a of the second holding member 112 and extendthrough the guide slots 114 a. The ring clamp 114 is capable of rotation(sliding movement) on the top surface of the second holding member 112.Specifically, the ring clamp 114 is rotated on the ring 112 a by a givenangle while being guided by the ring retainers (three retainers areshown). The arm 112 b of the second holding member 112 has one endpivotally connected to one side of the first holding member 111 by meansof a hinge mechanism 115.

With the wafer holder 110 thus constructed, the second holding member112 is pivoted through the hinge mechanism 115 and then, placed on thefirst holding member 111. The ring 114 is pushed or rotated in thedirection of arrow A. This rotation causes the protrusions 114 b toslide below the pawls 120. As a result, the first holding member 111 andthe second holding member 112 are clamped together.

With the first holding member 111 and the second holding member 112clamped together, the end projection 113 b is contacted with theperimeter edge of the semiconductor wafer held within the recess of thefirst holding member 111, as shown in FIG. 9. The other end projection113 c is in contact with the first holding member 111.

The second conductive element 118 is made of an electrically insulativematerial (such as synthetic resin) and takes a cylindrical shape. A slot118 a is formed in one end of the second conductive element 118 so thatthe second conductive element 118 has an inverted U-shape. The other,rear end of the second conductive element 118 is attached to the packing113 or the second holding member 112 through a spring 121. With thesecond holding member 112 placed on the first holding member 111, theend projection 118 b of the second conductive element 118 is in contactwith the conductive layer on the semiconductor wafer 116, whereas theend projection 118 c is in contact with the first conductive element117, as shown in FIG. 10. A conductive member 122 extends through thefirst holding member 111. The first conductive element 117 is connectedto the conductive member 122 which is, in turn, connected to an externalelectrode, not shown.

In this embodiment, the protrusions 114 b are arranged, at givenintervals, on the outer periphery of the ring clamp 114. Upon rotationof the ring clamp 114, the protrusions 114 b are slidably moved belowthe pawls 120 so as to clamp the first holding member 111 and the secondholding member 112 together. This arrangement enables uniformapplication of pressure on the packing 113 and thus, provides a betterseal. It will be noted that the first conductive element 117 isconnected to the conductive member 122 which is, in turn, connected toan external electrode, not shown.

In the embodiment shown in FIG. 10, the end projection 118 b of thesecond conductive element 118 is contacted with the conductive layer onthe semiconductor wafer 116, and the other end projection 118 c iscontacted with the first conductive element 117 when the second holdingmember 112 is superposed on the first holding member 111.

Alternatively, the first conductive element 117 may be omitted. As shownin FIG. 11, a conductive member 123 may be contacted with the conductivelayer of the semiconductor wafer 116. The conductive member 122 may alsoextend through the second holding member 112 and may be connected to theconductive member 123 through the spring 121.

The wafer holder 110 shown in FIGS. 7A, 7B, 8 and 9 may be used with theelectroplating system shown in FIG. 4.

The semiconductor wafer holder of the present invention is suitable foruse in the electroplating system.

In a conventional “dip-type” plating system, a semiconductor wafer mustmanually be mounted to a carrier or holder. However, a largersemiconductor wafer is difficult to mount by hand. There thus exists aneed for a fully automated electroplating system to plate an 8-inchsemiconductor wafer. In such a system, a start button is pressed tothereby automatically plate a wafer while a wafer cassette within whichthe wafer is mounted is placed in a given position. The wafer is,thereafter, loaded back into the wafer cassette.

FIGS. 12 and 13 show one form of an electroplating system for plating asemiconductor wafer. This system is suitable for use with the waferholder of the present invention. In FIG. 12, an electroplating system200 includes a wafer inlet 201 through which a wafer cassette isintroduced, a control panel 202 for controlling a loading/unloadingstation and a plating bath station, a signal tower 203, and an electricbox 204 electrically connected to the control panel 202.

In FIG. 13, the electroplating system includes a loading/unloadingstation 210 and a plating bath station 240. In the loading/unloadingstation 210, a wafer is removed from a wafer cassette and thereafter,removably mounted to the wafer holder. Also, the wafer is removed fromthe wafer holder and thereafter, loaded within the wafer cassette. Thewafer holder of the present invention enables the use of theloading/unloading station 210. In the bath station 240, the wafer holderis immersed in an electrolytic solution within a plating bath forelectroplating of the semiconductor wafer.

Again, an electroplating system according to a third aspect of theinvention provides a loading/unloading station whereby a wafer istransferred from a wafer cassette to the wafer holder, and the wafer istransferred from the wafer holder to the wafer cassette, and a platingbath station wherein the wafer is plated while the wafer holder isimmersed in an electrolytic solution within a plating bath.

The loading/unloading station 210 includes, among others, a cassettetable 212 on which a wafer cassette is placed, a wafer transfer robot216, a wafer centering device 218, and a spin dryer 219. Preferably, thecassette table 212 includes a sensor unit 214 for detecting theexistence of a wafer within a wafer cassette. The sensor unit 214includes a sensor for detecting as to whether or not a wafer is mountedin a given position within a wafer cassette, and a drive for moving thesensor. The sensor is typically moved in a vertical direction. The wafertransfer robot 216 is capable of removing a wafer from a wafer cassetteand transferring the wafer to a holder clamp. The wafer transfer robot216 is also capable of unloading the wafer from the holder clamp andtransferring the wafer to the wafer cassette. The wafer transfer robot216 is preferably moved for rotation. The spin dryer 219 is design todry a semiconductor wafer after it has been plated.

The loading/unloading station 210 includes one or more tables 220 withwafer loading/unloading tables 222 a, 222 b. The wafer loading/unloadingtable 222 a is moved to and away from the wafer loading/unloading table222 b, and vice versa. A holder clamp is mounted to the upper part ofthe wafer loading/unloading table 222 b. One form of the holder clamp isshown in FIGS. 14A and 14B. The loading/unloading station preferablyincludes a means (not shown) for detecting as to whether or not a waferis electrically connected to the wafer holder.

The electroplating system 200 includes a holder container 230 withinwhich holders 232 are contained. In the embodiment shown in FIG. 13, theholder container 230 includes upper and lower sections, with thirteenholders being contained in each section. The holder container 230preferably includes a sensor for detecting the existence of a holder.

The bath station 240 includes, among others, a plating bath 250, acleaning bath 260 and a dryer 270. The plating bath 250 preferablyincludes a plurality of compartments 252. In each compartment, oneholder within which a wafer is loaded is immersed in an electrolyticsolution for plating. Preferably, each compartment includes a portioninto which a holder is introduced, a unit for supplying electricalcurrent to the holder, and an anode. An exposed surface of the anodewhich is oriented to face with a wafer is preferably concentric with thewafer. A plurality of compartments may be agitated by a single agitator258. For example, an agitator rod may be moved in a direction parallelto the surface of a wafer to agitate two compartments. The agitator rodmay have variable speeds.

In the cleaning bath 260, it is preferable that pure water is caused toflow upwardly from its bottom so as to clean the holder and a platedsurface of the wafer within the holder. It is also preferable that theholder is quickly dumped into the cleaning bath so as to improve thecleaning result.

It is preferable to use the dryer 270 to dry the holder and a waferloaded within the holder. A suitable gas may be blown to remove waterdroplets from the holder and the wafer.

Thereafter, the holder is transferred to the holder loading/unloadingtables 222 a, 222 b. The wafer is removed from the holder and then,loaded within the wafer cassette.

The holder transfer robot is moved along a travel of path 280 so as tomove the holder between the loading/unloading station 210 and theplating bath station 240.

A HEPA filter is preferably attached to the ceiling (not shown) of theloading/unloading station 210 to cause fresh air to flow downwardly fromthe ceiling. This prevents the flow of steam from the plating bath 250to the loading/unloading station 210.

In the event of a failure, it is preferable to first develop an alarmsignal and give an indication to that effect and then, automaticallystop the electroplating system.

Operation of the electroplating system is as follows. First, a wafer isremoved from the wafer cassette. The wafer is then loaded into the waferholder. These steps thus include removal of wafer from the wafercassette and transfer of the holder 232 from the holder container 230 tothe wafer loading/unloading table 222 b.

More specifically, the wafer cassette is placed at a given location inthe loading/unloading station. The start button is then pressed to causea holder transfer robot (not shown) to move the holder 232 out of theholder container 230. The holder is then placed on the waferloading/unloading table 222 b. The wafer transfer robot 216 is operableto move a wafer out of the wafer cassette. The wafer is then placed onthe wafer loading/unloading table 222 b.

The holder clamp is then operable to load the wafer into the holder onthe wafer loading/unloading table 222 b. The wafer loading/unloadingtable 222 b is thereafter moved to an area where the waferloading/unloading station 222 a is located. The holder transfer robot(not shown) is operable to transfer the holder together with a waferfrom the wafer loading/unloading table 222 a to a compartment 252 in theplating bath 250. Electrical current is then supplied for apredetermined period of time so as to plate the wafer.

When the wafer has been plated, the holder transfer robot is operable totransfer the holder to the cleaning bath 260. After the wafer iscleaned, a gas is blown from the dryer 270 to remove water droplets fromthe wafer.

The holder transfer robot is again operable to transfer the holder tothe holder clamp. The wafer is, then, unloaded from the holder. Thewafer is, thereafter, introduced into a spin dryer 219. On the otherhand, the holder is transferred to the holder container 230. The waferis rinsed while it is rotated within the dryer. The wafer is,thereafter, rotated at a high speed to finalize the drying process.After the wafer has been dried, the wafer is returned to the wafercassette within which the wafer is originally loaded. When all thewafers are completely processed, a buzzing sound is produced, and thesystem is in a standby position.

FIG. 14A shows one form of the holder clamp. Specifically, a holderclamp 300 includes a drive, not shown, a rotary shaft 302 capable ofreciprocation along its own axis and rotation about its own axis, acircular disk 304 mounted on the shaft 302, and a circular disk 306fixed to the circular disk 304. The circular disk 306 includes a meansfor detachable engagement with the wafer holder. Illustratively, such ameans includes a plurality of pins 310 a, 310 b.

As shown in FIG. 14B, a wafer holder 320 includes holes 322 a, 322 b.The pins 310 a, 310 b are inserted into these holes 322 a, 322 b,respectively when the drive causes downward movement of the shaft 302.When the shaft is rotated in a clockwise or counterclockwise directionby a fixed angle, the pins 310 a, 310 b cause the wafer holder 320 torotate by a fixed angle. This rotation allows the wafer holder 320 toclamp or fasten a semiconductor wafer loaded in the wafer holder.Thereafter, the shaft 302 is lifted to disengage the pins 310 a, 310 bfrom the wafer holder.

In the embodiment shown in FIG. 8, for example, when the holder clamp300 is lowered, the pins 310 a, 310 b are inserted into the grooveswhere the ring retainers 119 are disposed. When the pins 310 a, 310 bare rotated by a fixed angle, the ring clamp 119 is rotated to clamp thering clamp 114 and thus, the semiconductor wafer.

Reverse operation causes the ring clamp 114 of the wafer holder 320 torotate in an opposite direction. This rotation loosens the ring clamp114.

The present invention provides the following advantageous effects.

In one aspect of the present invention, the semiconductor wafer 16 canreadily be mounted or loaded.

The packing has an inverted U-shape with opposite end projections placedin contact with the first holding member and the semiconductor wafer,respectively. The end projections collectively define a hole withinwhich the second conductive element is received. The second conductiveelement is mounted to the second holding member through a resilientmaterial. This arrangement provides a simple wafer holder with itselectrical contact reliably sealed by the packing.

The second conductive element has an inverted U-shape section withopposite end projections bridging between the first conductive elementof the first holding member and the conductive layer of thesemiconductor wafer. The second conductive element is mounted to thesecond holding member through a resilient material. This arrangementensures supply of electrical current to the conductive layer of thesemiconductor wafer.

In another aspect of the present invention, the ring clamp is employedto press the second holding member against the first holding member.This arrangement enables uniform application of pressure onto thepacking and provides a better seal.

The use of the inverted L-shaped pawls makes it easy to seal therequired part.

Additionally, the use of the hinge mechanism facilitates positioningbetween the first and second holding members.

Finally, the ring clamp is capable of rotation on the second holdingmember by a given angle. This configuration allows for ready positioningof the ring clamp relative to the pawls.

1. An electroplating apparatus comprising: a cassette table forloading/unloading a cassette containing a wafer therein; a wafer holderincluding a first holding member having a first conductive element and asecond holding member having a second conductive element, said first andsecond holding members for holding the wafer therebetween, wherein saidfirst conductive element is configured to supply electricity to saidsecond conductive element and said second conductive element isconfigured to supply the electricity from said first conductive elementto the wafer being held between said first holding member and saidsecond holding member; a wafer loading/unloading station configured tosupport said wafer holder for loading and unloading of the wafer to andfrom said wafer holder; a wafer transfer robot for transferring thewafer between said cassette table and said wafer loading/unloadingstation; wherein said wafer loading/unloading station is arranged so asto be within movable range of said wafer transfer robot so that saidwafer transfer robot is able to transfer the wafer to and from saidwafer holder supported on said wafer loading/unloading station; aplating bath configured to accommodate said wafer holder holding thewafer vertically and for holding a solution for plating an exposedsurface of a side of the wafer; and a holder transfer robot fortransferring said wafer holder, said holder transfer robot being movablebetween said plating bath and said wafer loading/unloading station. 2.An electroplating apparatus according to claim 1, wherein said firstconductive element and said second conductive element are in directcontact when said wafer holder is holding the wafer.
 3. Anelectroplating apparatus according to claim 1, wherein said wafer holderfurther includes a seal that seals a peripheral edge of the side of thewafer, an opposite side of the wafer, and said first and secondconductive elements from the solution.
 4. An electroplating apparatusaccording to claim 1, further comprising an anode that extends into saidplating bath, wherein the exposed surface of the wafer is electroplatedby supplying the electricity, via said first and second conductiveelements, between the exposed surface and said anode.
 5. Anelectroplating apparatus according to claim 4, wherein said wafer holderis positioned such that the exposed surface of the wafer faces saidanode.
 6. An electroplating apparatus according to claim 1, wherein saidplating bath includes an agitator for agitating the solution.
 7. Anelectroplating apparatus according to claim 1, wherein said plating bathincludes a plurality of compartments, each of said compartmentsconfigured to accommodate said wafer holder holding the wafervertically.
 8. An electroplating apparatus according to claim 7, furthercomprising a plurality of anodes, each of said anodes being located in arespective one of said compartments.
 9. An electroplating apparatusaccording to claim 1, further comprising a holder container for storingsaid wafer holder.
 10. An electroplating apparatus according to claim 1,further comprising a spin dryer for cleaning and drying the wafer, afterthe wafer is unloaded from said wafer holder, by rinsing with a cleaningliquid and drying after the wafer has been plated.
 11. An electroplatingapparatus according to claim 10, wherein said spin dryer spins the waferto clean and dry the wafer.
 12. An electroplating apparatus according toclaim 1, further comprising a cleaning bath for cleaning the exposedsurface of the wafer held by said wafer holder and said wafer holdertogether with a cleaning liquid.
 13. An electroplating apparatusaccording to claim 12, further comprising a dryer for drying the exposedsurface of the wafer held by said wafer holder and said wafer holdertogether after the cleaning with the cleaning liquid.
 14. Anelectroplating apparatus according to claim 1, further comprising a unitfor cleaning the exposed surface of the wafer held by said wafer holderand said wafer holder together with a cleaning liquid and drying theexposed surface of the wafer held by said wafer holder and said waferholder together after the cleaning with the cleaning liquid.